Isolate tenant readback cache and prepare verified runtime release

Assistant: codex
Assistant-Model: gpt-6.1-sol
Assistant-Session: 01a126e1-76f8-7643-8cf3-e93336539ade

tests/test_application_access.py

@@ -3,6 +3,7 @@ import json
 import os
 import tempfile
 import unittest
+from dataclasses import replace
 from datetime import UTC, datetime, timedelta
 from unittest.mock import patch
 from urllib.error import HTTPError, URLError
@@ -159,6 +160,21 @@ class ReaderTests(unittest.TestCase):
         reader.rows(_actor("alice"), "s1")
         self.assertEqual(len(readback.reads), 3)
 
+    def test_tenant_switch_cannot_reuse_another_tenants_allow(self):
+        readback = _FakeReadback([
+            ReadbackResult("informed-decision", "allow", NOW + timedelta(seconds=30), "decision:1"),
+        ])
+        reader = self._reader(readback)
+        actor = _actor()
+        self.assertEqual(reader.rows(actor, "s1")[0].status, "available")
+        readback.results = [ReadbackResult("informed-decision", "deny")]
+        other_tenant = replace(actor, tenant="tenant-b")
+        self.assertEqual(reader.rows(other_tenant, "s1")[0].status, "denied")
+        self.assertEqual(len(readback.reads), 2)
+        reader.forget("s1")
+        reader.rows(actor, "s1")
+        self.assertEqual(len(readback.reads), 3)
+
     def test_read_failure_is_unchecked_and_not_reused(self):
         readback = _FakeReadback([], fail_read=True)
         reader = self._reader(readback)